Device for treating, by heat tempering, a metal element of the tube or bar type having arched portions

ABSTRACT

The invention relates to a device for treating, by heat tempering, a metal element ( 1 ) of the tube or bar type having arched portions. The device includes heat treatment means having an induction coil ( 23 ) and a sprinkler ring ( 26 ). According to the invention, this device includes means ( 2 ) for holding the metal element ( 1 ) that is composed of a clip ( 2 ) arranged so as to clamp around an end portion, referred to as the top, of the metal element and to keep the metal element freely suspended under said clip. The device also includes multi-axis robots ( 24, 28 ) suitable for moving the induction coil ( 23 ) and the sprinkler ring ( 26 ) simultaneously along the metal element ( 1 ) starting from an end portion, referred to as the bottom, of the metal element that is opposite the top portion thereof.

BACKGROUND OF THE INVENTION

The invention relates to a thermal quenching treatment device for a metal element, tube or bar type, having curved sections.

More specifically, this invention relates to a heat treatment device comprising heat treatment means comprising an induction coil and cooling means composed of spray nozzles integrated in an annular sprinkler ring. The heat treatment device also includes holding means for holding the metal element and relative displacement means for the metal element holding means and heat treatment means adapted to generate a relative displacement of the metal element inside the induction coil and the sprinkler ring arranged close to each other.

According to a first solution, described in particular in US Patent Application Publication No. 2011/0284526, the thermal treatment devices comprise a fixed support on which a plurality of clamps, each composed of two jaws, are secured. The jaws are spaced from each other and arranged to be distributed along the longitudinal axis of the metal element. The jaws are adapted to be successively opened to allow for the displacement of the induction coil and the annular sprinkler ring along the metal element.

Such a solution makes it possible to ensure perfect retention of the metal element during its heat treatment which leads to limiting the possible deformations of this metal element caused by this heat treatment. A deficiency of this solution is that it requires specific tooling (support and clamps positioned on this support) for each model of the heat treated metal element, and is, therefore, a relatively expensive solution.

According to a second solution, in particular described in EP Patent No. 1 405 926, the heat treatment devices comprise a fixed induction coil and a multi-axis robot whose arm is equipped with a support on which are positioned a plurality of clamps arranged to be distributed along a portion of the longitudinal axis of the metal element. The clamps are spaced from each other so as to ensure the maintenance of the metal element during its passage through the induction coil. The heat treatment device also includes, a multi-axis robot on whose arm is mounted the sprinkler ring.

According to this solution, only a central portion of the metal element is held on the support equipped with the clamps so that several different models can be processed on a given support. However, the heat treatment of various models of metal elements requires the design of a range of supports. In addition, it turns out that because of their design (including fixed induction coil), such processing devices have limitations on the complexity of metal elements that can be heat treated.

SUMMARY OF THE INVENTION

The present invention aims at overcoming the disadvantages of the above-described devices for the heat treatment of metal elements. Its main purpose is to provide heat treatment devices designed to make it possible to treat, very simply, a wide range of metal elements by means of a single tooling. For this purpose, the invention provides a device for thermal-quenching treatment of a metal element, of the tube or bar type, having curved sections. The thermal quenching treatment device comprises a heat treatment device comprising an induction coil and cooling means. The cooling means comprises spray nozzles integrated in an annular sprinkler ring. The thermal quenching treatment device also includes a holding device for holding the metal element. The thermal quenching treatment device further includes a relative displacement device associated with the metal element holding device and heat treatment device to generate a relative displacement of the metal element inside the induction coil and the sprinkler ring, which are arranged close to each other. According to the invention, the holding device of the metal element is composed of a clamp arranged to grip an end section, the upper end, of the metal element, and to hold the metal element freely suspended under the clamp. The displacement device is composed of a displacement mechanism able to simultaneously move the induction coil and the sprinkler ring along a metal element suspended under the clamp, from an end section, the lower end, of the metal element opposite to its upper section.

This design, which consists of suspending the metal element by a holding device consisting of a simple clamp, and simultaneously moving the induction coil and the sprinkler ring along the metal element from its lower end, proves to lead to heat treatment, especially without causing interference between the heat treatment and cooling, of a wide range of metal elements that may have very complex shapes.

It should be noted, moreover, that during the treatment of metal elements liable to deform during this heat treatment, these deformations can be compensated, in a simple manner, by implementing a procedure consisting of, in a preliminary phase, carrying out the heat treatment of a sample of the metal element and measuring the deformations occurring during this treatment. Then, during the production of metal elements, these deformations are compensated for during machining, including bending, of the metal elements. After this the metal elements proceed to their heat treatment.

According to an advantageous embodiment of the invention, the clamp for holding the metal element is carried in a manner allowing for rotation of the clamp about an axis of rotation (x) able to give a movement oscillation of the metal element suspended under this clamp. In addition, the clamp holding the metal element is, advantageously according to the invention, carried by a displacement device allowing for at least one axis of translation.

A combination consists, moreover, advantageously according to the invention, to mount the displacement device for rotation of the clamp about an axis of rotation (x) on means for moving the clamp along a vertical axis of translation (z) and a horizontal translation axis (y).

The thermal quenching treatment device can also, advantageously according to the invention, comprise means for driving the clamp in rotation about a vertical axis (z). The degrees of freedom conferred on the clamp of the metal element offer additional possibilities of relative movement between the metal element and the induction coil/sprinkler ring assembly, and thus make it easier to maintain this element in the operating zone of the means for moving the induction coil and the sprinkler ring, and/or avoiding interference between the heat treatment and the cooling.

Furthermore, the displacement device of the induction coil is advantageously adapted, according to the invention, for an induction coil of a length so that the center of the median transverse plane of the induction coil is noticeably coaxial with the axis centered on the median plane of the neutral fiber Fn of the metal element. This mode of defining the trajectory of the induction coil, which consists in subtending this trajectory relative to the neutral fiber of the metal element, makes it possible to guarantee obtaining a minimum distance between the internal face of the induction coil and, respectively, the intrados and extrados of the metal element. This is possible for even very short radii of curvature of the order of 1, 5 to 2 times the diameter of the metal element, and leads to a significant increase in the range of metal elements that can be heat-treated by the treatment device according to the invention.

According to another advantageous embodiment of the invention, the induction coil and the sprinkler ring are each carried by a displacement device consisting of a multi-axis robot.

It should be noted, moreover, that the holding device of the metal element can also be carried by a displacement device consisting of a multi-axis robot adapted to confer several degrees of freedom in rotation and in translation. The heat treatment device according to the invention comprises, moreover, advantageously according to the invention, a multi-axis unloading robot provided with a clamp for gripping the metal element after heat treatment.

According to another advantageous embodiment of the invention, the clamp for holding the metal element consists of a tubular clamp adapted to cap and grip the upper portion of the metal element and to extend in the axial extension of the section superior thereto. In addition, this tubular clamp advantageously has, according to the invention, an outer diameter less than the respective internal diameters of the induction coil and the sprinkler ring, and is adapted to allow the axial displacement of the induction coil and the sprinkler ring along the tubular clamp. This tubular clamp design makes it possible to bring the induction coil and the sprinkler ring to a final position in which they extend around the tubular clamp, and thus release the entire length of the tube metal element.

Because of this possibility of bringing the induction coil and the sprinkler ring into such a final position, and firstly, only the end of the metal element gripped by the tubular clamp, a length of order of ten millimeters, does not undergo heat treatment. However, this end length is usually intended to undergo machining by forming and therefore does not need to be heat treated, so that the treatment device leads to treat, in one step, the entire length of the metal element requiring a heat treatment.

This final position also allows easy access to the metal element allowing its unloading by means of the unloading robot. Moreover, for the treatment of tubular elements, the thermal treatment device according to the invention advantageously comprises a source of cold fluid connected to inject a flow of cold fluid into the upper end section of the metal element, during the heat treatment of the latter. This injection of cold fluid into the upper portion of the metal element makes it possible to evacuate the hot vapors produced in the metaflique element during its cooling, and thus favors this cooling step.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the invention will become apparent from the detailed description which follows with reference to the accompanying drawings which show, by way of non-limiting example, a preferred embodiment. On these drawings:

FIG. 1 is a schematic perspective view of a thermal quenching treatment device according to the invention;

FIG. 2 is a perspective view of the means of this device for processing, holding and moving a metal element:

FIG. 3 is a longitudinal section through an axial plane of the clamp for holding a metal element and means for heat treatment of this metal element, represented positioned at the end of the treatment operation:

FIG. 4 is a cross section through a plane A of FIG. 3; and

FIG. 5 is an explanatory diagram of the mode of displacement of the induction coil.

DETAILED DESCRIPTION OF THE INVENTION

The treatment device according to the invention shown in the figures consists of a device for heat-quenching treatment of a metal element of the bar or tube type, such as a suspension element of a motor vehicle, which may notably consist of: shown in a torsion bar 1.

This thermal quenching treatment device comprises a holding device 2 for holding the metal element 1. The holding device 2 is composed of a clamp arranged to be positioned in the vicinity of an end section, the upper end, of the metal element so that the metal element 1 is kept freely suspended under the clamp. The thermal quenching treatment device also includes displacement devices for moving the clamp 2, on the one hand, in translation along a vertical axis (z) and along a horizontal axis (y), and on the other hand, in rotation around the vertical axis (z) and around a horizontal axis (x) perpendicular to the plane (y, z).

In the first place, the clamp consists of a tubular clamp 2 of the type of free cutting pliers comprising a part of revolution partially split along several generatrices, allowing, by its elasticity, to tighten on the outside of a cylindrical part of the metal element 1. In the example shown, this clamp 2 comprises an outer tube 10 having a flared end forming a conical seat 11 and an inner tube 12 pierced with a longitudinal axial bore 13. The longitudinal axial bore 13 is extended by a conical head 14 adapted to be housed in the seat 11 of the outer tube 10. The conical head 14 is provided with four radial slots such as to give it its elasticity. The conical head 14 has a front face in which is formed a countersink 16 for clamping the end of the metal element 1, and a displacement device for relative displacement of the outer tube 10 and the inner tube 12 between a loading position of a metal element 1 in the counterbore 16, in which the conical head 14 extends in the extension of the outer tube 10, and a clamping position of the end of the metal element 1, in which the conical head 14 is clamped in the conical seat 11.

In addition, the displacement device of the outer tube 10 and the inner tube 12 is adapted to move the outer tube 10 longitudinally along the inner tube 12. The displacement device consists of a jack 17 vertically connected to the outer tube 10 by a system of rods 18.

The displacement device of the clamp 2 is positioned on the vertical front face of a frame 3. The displacement device of clamp 12 comprises a first carriage 4 guided along vertical rails 5, and driven along the rails 5 by a motorized assembly (not shown), and a second carriage 6 carried by the first carriage 4, guided along horizontal rails 7 extending along axes (y) parallel to the front face of the frame 3, and driven along the rails by a motorized assembly (not shown). The displacement device also includes a gallow 8 rotatably mounted relative to the second carriage 6 about a horizontal axis (x) perpendicular to the front face of the frame 3. The gallow 8 is rotated by a motor assembly (not shown). The tubular clamp 2 is rotatably mounted within the gallow 8 for rotation around a vertical axis (z), by means of a motor 9.

In addition, the first carriage 4 is equipped with a retractable stand for stiffening the tubular clamp 2. The first carriage comprises a support piece 19 mounted on the end of the two rods 20 a of a jack 20 arranged along an axis (x), whose body 20 b is secured to the first carriage 4.

In addition, this support piece 19 comprises a housing 21 of a shape adapted to house the lower end of the tubular clamp 2. In the lower extension of housing 21 is formed a groove 22 intended to house the upper section of the suspended metal element 1 under the tubular clamp 2.

The thermal quenching treatment device further comprises a heat treatment device and a cooling device of the type described in the European Patent EP 1 405 926, and thus constituted, respectively, of an induction coil 23 and an annular sprinkler ring 26 in which are integrated spray nozzles 27. Displacement devices are provided to simultaneously move the induction coil 23 and the sprinkler ring 26 along the metal element 1 suspended under the tubular clamp 2, from the lower end section of the metal element 1.

The displacement device comprises, for each of the two elements, that is, the induction coil 23 and the sprinkler ring 26, a multi-axis robot 24, 28 shown schematically in FIG. 1. Each of the multi-axis robots 24, 28 comprise, in a conventional manner, a terminal arm 25, 29 provided with a gripping member for the induction coil 23 and the sprinkler ring 26.

The thermal quenching treatment device furthermore comprises, as shown diagrammatically in FIG. 3, a third multi-axis unloading robot 30 equipped with a terminal arm 31 equipped with a gripper 32 for gripping the metal element 1 after heat treatment. The treatment device comprises, finally, an air source 33 connected to inject a cold air flow into the upper end section of the metal element 1 during the heat treatment of the metal element 1.

According to the principles underlying the thermal quenching treatment device of the present invention, and first of all, with a view to its heat treatment, the metal element 1 is suspended under the tubular clamp 2. The heat treatment is then carried out by simultaneously moving the induction coil 23 and the sprinkler ring 26 along the metal element 1 from the lower end section of the metal element 1. Optionally, the simultaneous movement of the induction coil 23 and the sprinkler ring 26 along the metal element 1 may be by combined with displacements in translation along the axis (y) and/or along the axis (z), and/or rotations around the axis (x) and/or the axis (z) of the tubular clamp 2. Such displacement is intended to allow the metal element 1 to be held in the operating zone of the two multi-axis robots 24, 28, and/or to avoid interference between the heat treatment and the cooling.

During this heat treatment, moreover, when the metal element 1 consists of a tubular element, cold air is injected into the upper section of the metal element 1, thus making it possible to evacuate the hot vapors produced in the metal element 1 during its cooling, and thus promoting this cooling step.

In addition, during this heat treatment, the displacement of the induction coil 23 and, possibly, of the tubular clamp 2 are controlled, as shown in FIG. 5, for the length of the induction coil 23, so that the center of the median transverse plane of the induction coil 23 (that is to say the transverse plane located at half-length ½ of the induction coil 23), is at least substantially coaxial with the neutral fiber Fn of the metal element on the median plane thereof (that is to say the longitudinal axis ½ on either side of the median plane). The trajectory conferred on the induction coil 23 according to this principle 25 makes it possible to guarantee obtaining a minimum distance between the internal face of the induction coil 23 and the intrados and the extrados of the metal element 1, even for very short radii of curvature of the order of 1.5 to 2 times the diameter of the metal element. The simultaneous displacement of the induction coil 23 and the sprinkler ring 26 is further adapted to bring the induction coil 23 and the sprinkler ring 26 to a final position, shown in FIG. 3, in which they extend around the tubular clamp 2. Due to the possibility of bringing the induction coil 23 and the sprinkler ring 26 into such a final position, the end of the metal element 1 clamped in the countersink 16 of the tubular clamp 2, a length of the order of ten millimeters, is not subjected to heat treatment.

However, this end length is usually intended to undergo machining by forming and therefore does not need to be heat treated, so that the treatment device leads to treat the entire length of the metal element 1 requiring a heat treatment. This final position also allows easy access to the metal element 1, allowing its unloading by means of the unloading robot. 

1. A thermal quenching treatment device of a metal element, of the tube or bar type, having curved sections, comprising: a heat treatment device comprising an induction coil and a cooling device comprising spray nozzles integrated into an annular sprinkler ring, a holding device for the metal element, and a displacement device, the holding device and the heat treatment device are adapted to produce a relative displacement of the metal element inside the induction coil, and the annular sprinkler ring is arranged in close proximity to both the holding device and the heat treatment device, the holding device for maintaining the metal element is composed of a clamp arranged in such a way as to tighten a stretch of an end of the metal element, and to maintain the metal element freely suspended under the clamp, and there is provided a travel device that is capable of simultaneously moving the induction coil and the annular sprinkler ring along the metal element suspended under the clamp, from an end section of the metal element opposite to an upper section.
 2. The thermal quenching treatment device according to claim 1, wherein the clamp retaining the metal element is carried by a rotational drive of the clamp around a rotation axis (x), capable of conferring an oscillation motion at the metal element suspended under the clamp.
 3. The thermal quenching treatment device according to claim 1, wherein the clamp retaining the metal element is carried by displacement of the clamp according to at least one axis of translation.
 4. The thermal quenching treatment device according to claim 3, wherein rotational drive of the clamp is around an axis of rotation (x) carried by movement of the clamp according to a vertical translation axis (z) and a horizontal translation axis (y).
 5. The thermal quenching treatment device according to claim 1, further comprising a rotating drive of the clamp around a vertical axis (z).
 6. The thermal quenching treatment device according to claim 1, wherein a displacement of the induction coil is adapted so that a center of a plane that is transverse of the induction coil is at least substantially coaxial with a median plane of a neutral fiber Fn of the metallic element.
 7. The thermal quenching treatment device according to claim 1, wherein the induction coil and the annular sprinkler ring are carried by a multi-axis robot.
 8. The thermal quenching treatment device according to claim 1, further comprising a multi-axis robot unloading with a clamp for the attachment of the metal element after heat treatment.
 9. The thermal quenching treatment device according to claim 1, wherein the clamp retaining the metal element consists of a tubular clamp suitable for styling and tightening the upper section of the metal element and extending into an axial extension of the upper section.
 10. The heat treatment device according to claim 9, wherein the clamp has an external diameter lower than respective internal diameters of the induction coil and the sprinkler ring, suitable to allow axial displacement of the induction coil and the annular sprinkler ring along the clamp.
 11. The thermal quenching treatment device according to claim 1, wherein the heat treatment device includes a source of cold fluid connected in such a way as to inject a cold fluid flow into an end section of the metal element, during the heat treatment. 